The present invention relates to a peripheral pump and, more particularly, to a peripheral pump for feeding fuel to an internal combustion engine from a fuel tank of a motor vehicle.
A peripheral pump for feeding fuel from a tank of a motor vehicle to an internal combustion engine is known comprising an impeller rotatable in a rotation direction, having a rotation axis and including a plurality of blades extending radially from a rim of the impeller and spaced from each other in the rotation direction of the impeller; and a pump chamber for the impeller. The pump chamber has at least one chamber wall facing in a direction of the rotation axis. At least one chamber wall or walls have a ring-shaped duct therein spaced radially from the rotation axis to the same extent as the blades.
One example of the above-described type of peripheral pump is described in German Patent 10 05 374. This peripheral pump has an impeller rotatable in a pump chamber which has a rim from which a plurality of blades extend radially spaced from each other. The pump chamber is bounded by two walls which face in a direction along a rotation axis of the impeller, a ring-shaped entrance duct for fluid flow being formed in at least one of the two walls. The rear side of each blade directed opposite to the rotation direction of the blade has a curved surface as seen in a tangential cross-section taken along the impeller periphery. Thus the surface on the rear side of the blade can be viewed as inclined on average relative to the bounding wall, so that the surface in an edge region facing the chamber wall is directed oppositely to the rotation direction of the impeller. The front side of each blade directed in the rotation direction of the impeller is similarly curved, so its edge region pointing at the bounding wall leads the edge region pointing away from the bounding wall. The flow of the medium to be pumped into the intervening space between the blades occurs from the duct formed in the bounding wall in a direction opposite to the rotation of the impeller. Because of the curved structure of the rear side of the blade, the flow of the medium into the intervening spaces formed between the blades is not parallel to the surface of the rear side of the blade so that nonlaminar flow occurs on the rear side of the blade and turbulence occurs, which is drawn from the kinetic energy of flow and is dissipated as heat. These loses, so-called shock losses, reduce the pressure head obtained and the efficiency of the pump.